In the surgical repair of soft tissue such as the surgical reattachment of ligaments to bone or the attachment of tendon to muscle, it is known to use devices that surgically fasten the soft tissues to be repaired to the bone so as to avoid the use of suture knots. Suture knots are disadvantageous because the knot weakens a portion of the suture and reduces the overall force transmitting capability of the suture. Additionally, suture knots can also exhibit the phenomenon of “creep,’ where the suture can slip though the knot, resulting in a loss of tension in the suture. Suture creep can cause a change in orientation or misalignment of the attached tissue resulting in an improper healing of the attached tissue and/or pressure on or trauma to surrounding tissue.
Additionally, as a number of procedures are performed with limited surgical access, it can be difficult to form an appropriate suture knot. Furthermore, such a knot may not be uniformly tensioned and thus may slip or bind and cause pressure on or trauma to surrounding tissue.
In contrast, a fastener can be used to maintain a suture in a desired position relative to body tissue as long as the suture can be appropriately tensioned prior to its fixation and held in this tensioned state. For example, the fastener may be affixed to the suture in a manner that maintains the suture under tension. For instance, the fastener may be heated until its material reaches its transition temperature range and then plastically deformed. As the material is heated, it changes from a solid condition, in which it has a fixed form, to a soft or viscous condition. The soft or viscous material can be molded around an outer side surface of a suture and bonded to the suture without significant deformation of the suture. The transition temperature of the fastener may vary according to the material used. Some examples of various polymers which are suitable for forming fasteners are disclosed in U.S. Pat. No. 5,735,875, which is incorporated herein in its entirety. The fixation of the fastener prevents suture creep, maintaining the attached tissue in the proper orientation.
The use of fasteners helps avoid some of the deficiencies that may result from using only suture knots. One primary benefit of using fasteners is that they help properly tension the suture prior to fixation, which in turn may substantially reduce the likelihood of tensioned slip or binding of the suture that can cause excessive pressure on or trauma to the surrounding tissue. Additionally, fasteners can be used in limited access procedures.